A wide variety of dielectric films are used in microcircuit technology today. Many of these films are deposited on the semiconductor in which the microcircuit is formed. However, others are grown out of the semiconductor itself and are referred to be native films. The principle advantage of these native films is that they are relatively free of contaminants. This is because they are grown under consumption of the pure semiconductor in hyperpure gas ambients where impurity concentrations are limited.
Native films are widely used in semiconductor manufacturing because of their ease of formation and excellent interface with the underlying substrate. In silicon the basis of all device surface passivation is the native SiO.sub.2, though other insulating deposited films are useful as secondary layers in microcircuit fabrication. Furthermore, thermally grown oxides are used for masking, screen oxides, device isolation and for tunnel or gate dielectrics. This wide variety of applications led to intensive studies of the electrical properties and growth kinetics of silicon dioxide in the past years as published in detail in B. E. Deal and S. Grove J. Appl. Phys. 36 (12), 3770-3778 (1965) and P. Balk, THE SI--SiO.sub.2 SYSTEM, Elsevier Science Publishing, Amsterdam, 1988.
Most of these investigations concentrated on conventional furnace oxidations in purified dry oxygen (H.sub.2 O content less than 10 ppm) or in wet oxygen ambients, as detailed in the above references and in B. E. Deal, J. Electrochem. Soc. 125 (4), 576-579, (1978). With the introduction of the first rapid thermal processing systems several years ago, the first Rapid Thermal Oxidation (RTO) data in dry oxygen ambient were presented by M. M. Moslehi, S. C. Shatas and K. C. Saraswat, Appl. Phys. Let. 47 (12), 1353-1355 (1985).
For the growth of thick dry silicon dioxides too much time-temperature of the thermal budget is necessary. For example, a 1150.degree. C. treatment for 90 sec is necessary to produce a 19.3 nanometer (nm) SiO.sub.2 film on the silicon surface. These very high time-temperature combinations may cause problems concerning the electrical properties achieved prior to oxidation, so a reduction of the time-temperature combination during oxidation is indispensable.
Moslehi et al. reported in the Texas Instrument Technical Journal 9(5) 44-64, (1992) on wet oxidations performed near atmospheric pressure (650 Torr) for the initial growth of 25 nm mask oxides for CMOS well processing. M. Glueck, U. Koenig, J. Hersener, Z. Nenyei and A. Tillmann Mat. Res. Soc. Symp. Proc. 342 215-225 (1994) used a bubbler system with deionized water to run wet oxidation in a Rapid Thermal Processing (RTP) system. However, the repeatability of the bubbler method was poor because of insufficient control of the H.sub.2 O partial pressure. Higher metal contamination and particle density are also associated with this method.
These serious problems have been solved by combining an RTP system with a pyrogenic steam generator which is well known from conventional furnace technology. The impurity concentration only depends on the contamination residuals in the gas. The resulting oxides are, however, of lesser quality than the oxides produced in conventional furnaces. The present invention is a method of raising the quality of the wet oxides and other native and non-native films produced in an RTP system to the maximum possible.